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Road congestion on locally managed ‘A’ roads is measured by estimating the average speed achieved by vehicles during the weekday morning peak, from 7am to 10am. Average speeds are presented at national, regional and local highway authority level.

Average speed, average delay and the reliability of travel times on Highways England’s motorways and ‘A’ roads are brought together in the travel time measures on the strategic road network release. Statistics are currently presented at a national level only.

Statistical releases for both congestion on locally managed ‘A’ roads and travel time measures on Highways England’s motorways and ‘A’ roads are published on a quarterly basis (in February, May, August and November). The statistical datasets supporting are also updated on a quarterly basis.

Technical information

These statistics used to monitor road congestion and journey time reliability are compiled from journey time data from in-vehicle global positioning systems (GPS) and flows estimated using automatic traffic counters and the department’s manual traffic count data.

The road congestion and travel times statistics guidance contains a brief introduction into these statistics, including what they measure, how they are published and how they are used. The guidance also includes technical information relating to the reliability of journeys on the Highways England’s network and on locally managed ‘A’ roads, plus information on public attitudes and research and development.